Harvested Rainwater Might Help Relieve Water-scarcity Concerns
Rainwater harvesting, or, the collection of rainwater for later use, could be more than a drop in the water-conservation bucket for Southern California.
That's why five of University of California Riverside's (UCR) newest alumni in chemical and environmental engineering returned to campus following the New Year's holiday to do manual labor -- installing catch basins, piping, downspouts, and storage tanks at the Bourns College of Engineering at UCR.
Their concept has attracted regional and national attention. The Metropolitan Water District (MWD) of Southern California and the U.S. Environmental Protection Agency have each awarded the group $10,000 grants.
Now, group members Andrew Chin, Roland Cusick, Steven Gebelin, Greg Guillen, and Temi Ogunyoku are building a prototype system on the roof of Bourns Hall that will collect, store, and use collected rainwater to irrigate the lawns around the Bourns College of Engineering at UCR. They are working with advisors: Kawai Tam, a lecturer in the department of chemical and environmental engineering, and college of engineering Associate Dean Mark Matsumoto.
The group will present its findings to the MWD in late February and will compete in Washington D.C. on May 9 and 10, 2006 against 40 other student design teams. At stake are a top rating by a panel of National Academy of Sciences judges, a $75,000 development grant for the winning concept, and receipt of the national P3 (People, Progress and the Planet) Award.
UCR team members developed their idea from an off-hand remark made during a discussion about an upcoming class project.
"Temi jokingly came up with the idea of using Dixie cups to collect water, and that lead, through our discussions with Dr. Matsumoto, to the idea of rainwater harvesting," said Cusick. "The problem was that, as Southern California gets paved over, we're diverting more of our rainwater to runoff and less is getting into groundwater (aquifers)."
Guillen added: "We started discussing clean water sources and realized the closest source was rainfall and its first contact is rooftops."
Andrew Chin is doing environmental assessment work for the Cabazon Band of Mission Indians in Indio. Cusick is spending this year as a ranger at Glacier National Park in Montana before applying to graduate school. Steven Gebelin is attending New York University's Law School. Greg Guillen is a first-year PhD student in civil and environmental engineering at UCLA. Ogunyoku is a first-year master's student in wastewater treatment at UC Davis.
The group looked at Ontario, Calif. as their model because of its rapid growth, adequate rainfall, and large numbers of warehouses and distribution centers with large roof surface areas. Currently, Ontario gets 70 percent of its water from underground aquifers and buys the other 30 percent from MWD.
Ontario is one of eight municipal water suppliers operating under the auspices of the Inland Empire Utilities Agency. The agency has set a goal of saving, through conservation, more than 25,000 acre-feet of water, or about seven percent of current use, over the next 20 years.
The UCR group thinks rainwater harvesting can help meet those goals, and can be used in other countries where water is scarce, but they have to have solid numbers, and that's where the Bourns Hall experiment comes in.
Computer models suggest that, the college's 795-square-foot lawn could be irrigated with harvested rainwater for 237 days, or 65 percent, of the year. That amounts to an annual savings of about $955 to the college's water bill over those five years.
For the City of Ontario, the group thinks rainwater harvesting could ideally collect more than 2,200 acre-feet of water per year, enough to meet the domestic water needs of nearly 10,000 people annually.
For more information, visit www.ucr.edu .
Global Warming Blamed for Ancient Reversal of Ocean Currents
For the first time, evidence that global warming triggered a reversal in the circulation of deep ocean patterns around the world has been uncovered by scientists affiliated with the Scripps Institution of Oceanography. While the changes they describe occurred 55 million years ago, the scientists say today's conditions are similar and could have similar drastic effects on ocean circulation.
In the Jan. 4 issue of the journal Nature scientists Flávia Nunes and Richard Norris describe how they examined a four- to seven-degree warming period that occurred some 55 million years ago during the closing stages of the Paleocene and the beginning of the Eocene eras.
"The Earth is a system that can change very rapidly," Nunes said. "Fifty-five million years ago, when the Earth was in a period of global warmth, ocean currents rapidly changed direction, and this change did not reverse to original conditions for about 20,000 years."
The global warming of 55 million years ago, known as the Paleocene/Eocene Thermal Maximum (PETM), emerged in less than 5,000 years, an instant of geological time.
Modern carbon dioxide input to the Earth's atmosphere from fossil fuel sources is approaching the same levels estimated for the PETM period, according to the scientists, which raises concerns about future climate and changes in ocean circulation.
They say the Paleocene/Eocene example suggests that changes produced by human activities may have lasting effects not only on global climate, but on deep ocean circulation.
Fossil records show that the global warming at the time of the PETM created changes ranging from a mass extinction of deep-sea, bottom-dwelling marine life to migrations of terrestrial mammal species, as warm conditions may have opened travel routes frozen over when climates were colder. This time period is when scientists find the earliest evidence of horses and primates in North America and Europe.
Nunes and Norris base their findings on the chemical makeup of microscopic sea creatures that lived 55 million years ago.
The scientists analyzed carbon isotopes, or chemical signatures, from the shells of the one-celled animals called foraminifera, or "forams," that exist in vast numbers in a variety of marine environments.
"A tiny shell from a sea creature living millions of years ago can tell us so much about past ocean conditions," Nunes said. "We know approximately what the temperature was at the bottom of the ocean. We also have a measure of the nutrient content of the water the creature lived in. And, when we have information from several locations, we can infer the direction of ocean currents."
In the study, the scientists looked at a foram named Nuttalides truempyi from 14 sites around the world in deep-sea sediment cores retrieved via the Integrated Ocean Drilling Program.
Chemicals from the foram's shells were used as nutrient "tracers" to reconstruct changes in deep ocean circulation through the ancient time period.
Nutrient levels tell the researchers how long a sample has been near or isolated from the sea surface, giving them a way to track the age and path of deep sea water.
Nunes and Norris found that deep ocean circulation in the Southern Hemisphere abruptly stopped the conveyor belt-like process known as "overturning," in which cold and salty water in the depths exchanges with warm water on the surface.
Even as it was shutting down in the south, overturning appears to have become active in the Northern Hemisphere.
The researchers believe this shift drove unusually warm water into the deep sea, likely releasing stores of methane gas that led to further global warming and a massive die-off of deep-sea marine life.
"Overturning is very sensitive to surface ocean temperatures and surface ocean salinity," said Norris, a professor of paleobiology in the Geosciences Research Division at Scripps. "The case described in this paper may be one of our best examples of global warming triggered by the massive release of greenhouse gases, and therefore, it gives us a perspective on what the long term impact is likely to be of today's greenhouse warming that humans are causing."
Overturning is a fundamental component of the global climate conditions we know today, said Bil Haq, program director in the National Science Foundation's division of ocean sciences, which funded the research.
Haq says overturning in the modern North Atlantic Ocean is a primary means of drawing heat into the far north Atlantic and keeping temperatures in Europe relatively warmer than conditions in Canada.
Today, deep water generation does not occur in the Pacific Ocean because of the large amount of freshwater input from the polar regions, which prevents Northern Pacific waters from becoming dense enough to sink to more than intermediate depths.
But in the Paleocene/Eocene, deep-water formation was possible in the Pacific because of global warming, the researchers say, adding that the Atlantic Ocean could also have been a significant generator of deep waters during this period.
For more information, visit www.sio.ucsd.edu.
This article originally appeared in the 03/01/2006 issue of Environmental Protection.